Spring-operated spray gun



Patented May 20,1952

UNITED S TATES PAT E'NT OFFICE SPRING-OPERATED SPRAY GUN George B. Maehren, Seattle, Wash.

Application October 17, 1947, Serial No. 780,414

2 Claims.

This invention relates to a spray gun and an object of this invention is to provide a spray gun or like device in which spring pressure is used to spray liquid from a discharge nozzle.

A further object is to provide a spray gun or like device having a conical spring provided with means which will cause the coil section of the spring to release and expand one section at a time thus providing'better' and more uniform spring pressure.

Further objects are to provide a spray gun of simple and efficient construction which is not expensive to manufacture, which is easy to operate, which will eliminate the necessity for the use of compressed air in spraying and which is adapted to garden use, paint spraying, fuel spraying or spraying any other liquid.

Other objects willbe apparent from the following description taken in connection with the accompanying drawings.

In the drawings:

Figure l'is a vertical section of a spray gun constructed in accordance with this invention, parts being shown in elevation.

Fig. 2 is a fragmentary sectional viewon a larger scale than Fig. 1 showing spring coil holding and releasing devices.

Fig. 3 is a detached perspective of a spring coil holding device.

Fig. 4 is a fragmentary sectional view of an alternative spring.

Like reference numerals designate like parts throughout the several views.

This spray gun comprises a cylindrical receptacle 5 having a removable cap or cover portion 6. Preferably the cover portion 6 is threaded onto the receptacle 5 and a gasket 1 is used to provide a liquid tight seal between these two parts. A piston, which may comprise two plate members '8 and 9 and a cup leather'or rubber l secured together by screws H is provided in the receptacle 5.

A compression spring i2 is provided in the receptacle below the piston for the purpose of urging the piston upwardly. Preferably the spring [2 is made from spring steel of flat rectangular cross section wound spirally so that the coils of said spring will fit one within another when the spring is fully compressed, that is when all of the coils of said spring are in the same plane. The conical spring I2 shown in Fig. 4 is made of spring metal of uniformly decreasing cross sectional area from the larger to the smaller end of the spring. This provides uniformity of stiffness throughout the length ot aspring of Fig. 1. pressed to an over all length substantially equal variable diameter. Spring l2 can be used in place of spring I2. When the spring (l2 expands the coils assume a conical form, as shown in This 'provides'a spring that can be comto the width of one coil. Thus the spring I2 will occupy very little space longitudinally of the receptacle 5 when it is compressed and the over all length of a receptacle 5 of predetermined capacity can be reduced to a minimum.

providing about three and three fourths inches of piston travel.

The means for holding or latching together adjacent laps of the coil of the spring I2 when this spring is compressed and then successively releasing said laps or coil portions as the spring expands, comprises a plurality of curved spring plates each carrying a pin 36. Each pin 33 extends through a small hole 31 in one coil of said spring and is adapted to have its rounded end 33 seat in a substantially semi-spherical recess 39 in an adjacent coil. Preferably the holding devices are installed in oifset or staggered relation around the spring. Several of these holdingdevices are shown in diametrically opposite relation in the drawings. When the spring I2 is fully compressed the pins 36 of all of these holding devices will seat in the respective recesses 38'with which they are aligned. Also when the spring is fully compressed all of the bowed spring plates 35 will be flattened and will lie between the coils of the spring and the pins '36 will be held within their respective notches. As the piston begins to move upwardly the innermost or top coil portion of the spring l2 will begin to move out of engagement with the uppermost holding device. When this occurs the spring plate 35 of this uppermost holding device will begin to assume its normal curved shape and the pin 36 thereof will be retracted and the holding device released. This allows expansion of the coil portions previously restrained by the first holding device and eventually results in a similar releasing of the second holding device. The releasing of successiveholding devices continues in this way as the piston moves upwardly until all-'of said-holding devices have been released. A more desirable spring action has been obtained by thus holding the coil of the spring I2 at spaced intervals and successively releasing the holding devices.

The upper end portion of the spring I2 abuts against the lower side of the lower piston plate 8. Preferably the upper piston plate 9 is relatively thick and preferably the upper surface of said upper piston plate 9 is of convex shape. This thick plate 9 fills most of the space in the cup leather I9 and comes in close proximity to and preferably contacts the cover 6 when the piston is at the top limit of its stroke. Thus it is possible to eject substantially all of the liquid from the receptacle as the piston moves upwardly.

Each piston plate 8 and 9 is provided with a centrally disposed threaded opening I3 for receiving the end portion of a threaded piston retracting bolt or screw I4 that is used for retracting the piston. This piston retracting bolt I4 is readily removable after the piston has been retracted and a charge of liquid introduced. The thread on the bolt I4 is diagrammatically shown. I prefer to use a square or acme thread on this bolt but an ordinary tapered thread can be used if desired. A nut I5, preferably provided with a crank arm I6 by which it may be turned, is threaded onto the bolt I4. The nut I5 and arm I6 constitute a threaded crank but obviously an ordinary nut can be used and can be turned with a wrench. When the bolt I4 is to be used to retract the piston said bolt is inserted through a perforation I1 in the bottom I8 of the receptacle 6 and is screwed into the threaded openings I3 of the piston plates 8 and 9. The crank I'5-I 6 is then turned to draw the piston toward the bottom of the receptacle 6 and compress the spring I2.

After the piston has been fully retracted the space in the receptacle 6 above said piston can be filled with liquid, either by removing a plug 4 in the cover 6 or by removing said cover from the receptacle 5. After the receptacle 5 has been filled either the plug 4, or the cover 6 if it has been removed, is applied and sealed. The crank I5--I6 is then retracted on the bolt I4 leaving the liquid under the full pressure exerted by the spring I2. The bolt I4 can then be unscrewed from the plates 8 and 9 and removed if desired. Preferably a head I9 is provided on the lower end of the bolt I4 and this bolt I4 can easily be unscrewed from the plates 8 and 9 by reversely rotating the crank I5I6 until the nut part I5 jams against the head I9 and thereafter using the crank I5--I6 as a means for unscrewing said bolt I4 from the plates 8 and 9.

The cover 6 has a nozzle member 29 that is provided with a liquid outlet opening 2|. A needle type valve member 22 is provided for regulating the size of the opening 2| or for entirely closing said opening 2 I. An adjustable cap 23 is screw threaded onto the nozzle member 20. The cap 23 is shaped so as to provide a chamber 24 between it and the nozzle member 20. A discharge opening 25 is provided in the cap 23. The shape of this opening 25 determines the shape of the spray that will be emitted. If this opening 25 is of narrow rectangular shape a fan shaped spray will be emitted. If said opening 25 is circular a cone shaped spray will be emitted. The cap 23 is adjustable on the nozzle member and preferably a lock nut 33 is provided to lock said cap 23 in any desired adjusted position. If the cap 23 is moved outwardly on the nozzle member 20 a wider spray will be emitted. If said 4 cap is moved inwardly on member 20 then a narrower spray will be emitted. The chamber 24 has been found useful in helping to provide a more finely divided and better spray.

The valve 22 extends to the right, Fig. 1, through a tubular fitting 26 and through a packing gland 2'! and outwardly to the exterior of the cover 6 and through a forked trigger member 29. The forked trigger member 29 engages within an annular groove 28 in the valve 22. This provides a self adjusting connection between the valve 22 and the trigger 29 so that the valve can be longitudinally moved by movement of the trigger 29 and at the same time said valve is always free to turn and can always stay in correct alignment with the fitting 26. The trigger 29 is pivotally connected by pivot means 30 with a handle 3|. The handle 3| is shaped somewhat like the handle of a pistol. The handle 3I is integral with or rigidly connected with the cover 6.

Preferably the outer end portion of the valve 22 extends into an opening 34 in the handle 3I. A compression spring 32 is positioned on the valve 22 between the trigger 29 and handle 3|. By exerting a pull to the right, Fig. 1, on the trigger 29 the valve 22 can be opened any desired amount and when the valve 22 is thus opened the pressure of the spring I2 will cause a spray of finely divided liquid to be discharged from the opening 25. As soon as the pull on the trigger 29 is released the spring 32 will close the valve 22. Preferably a hook 40 is provided on the handle 3| to facilitate hanging the spray gun on any suitable support. Also preferably finger grips H are provided on the handle 3I. These grips are useful in preventing turning of the handle 3| in the hand.

This spray gun is particularly well adapted for garden use in the spraying of flowers, vegetables and the like where ordinary hand sprayers are used. However it will be understood that the same can be used for other purposes.

This spray gun can be charged by retracting the piston, removing the plug 4, or removing the entire cover 8, introducing the liquid to be sprayed, replacing and sealing either the plug 4 or the cover 6, and retracting the crank I5-I6 to allow the force of the spring I2 to be exerted against the liquid. The bolt I4 will protrude a substantial distance from the bottom of the receptacle 6 when the spring I2 is fully compressed and for this reason said bolt I4 will usually be removed after the gun is filled and before the gun is used for spraying.

In the use of the gun for spraying, the piston will move upwardly as the liquid is discharged and the coils of the spring I2 will be released one after another thereby providing a more constant spring force than I have been able to obtain without the use of the spring holding and releasing devices.

When the piston reaches the upper end of its stroke the convex upper surface of the upper plate 9 will rest against the cover 6 as shown in Fig. l and the piston will be stopped before the spring I2 is fully expended and while there is still a strong pressure exerted by said spring.

The foregoing description and accompanying drawings clearly disclose a preferred embodiment of my invention but it will be understood that changes in the same can be made within the scope of the following claims.

I claim:

1. In apparatus of the class described, a conically shaped spirally wound one piece compression spring adapted to be interposed between two relatively movable members, said spring being formed of flat spring metal of substantially rectangular cross section and the coils of said spring being adapted to telescope relative to each other when the spring is compressed, whereby the spring will occupy a minimum amount of space; coil holding latch means carried by coil portions of said spring; and latch receiving recesses provided in other coil portions of said spring adjacent to and in registration with the latch means when said spring is compressed, the latch means being adapted to engage within the recesses and releasably connect the coil portions of said spring together when the spring is compressed and to release the coils of said spring successively from one end of the spring as said spring expands.

2. In apparatus of the class described, a conically shaped spirally wound one piece compression spring adapted to be interposed between two relatively movable members, said spring being formed of flat spring metal of substantially rectangular cross section and the coils of said spring being adapted to telescope relative to each other when the spring is compressed whereby the spring will occupy a minimum amount of space, coil portions of said spring having transverse perforations provided therein and other coil portions of said spring having approximately semispherical recesses positioned in alignment with said transverse perforations; latch pins slidably disposed in said transverse perforations, each latch pin having one rounded end portion adapted to engage within an adjacent semi-spherical recess; and a concavo-convex latch pin spring of fiat metal attached to the other end portion of each latch pin with the concave side thereof toward the latch pin and with the latch pin spring operatively disposed between adjacent coil portions of the compression spring, whereby when said compression spring is compressed the latch pin springs will be flattened between adjacent coil portions of the compression spring and the rounded end portions of the latch pins will be engaged within the semi-spherical recesses and will releasably latch the coil portions of said compression spring together, and whereby as said compression spring expands the latch pin springs and latch pins will be released successively from one end toward the other of said compression spring and will successively release the coils of said compression spring.

GEORGE B. MAEHREN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 650,310 Dunning May 22, 1900 FOREIGN PATENTS Number Country Date 89,170 Germany Oct. 28, 1896 

